Crushing mills are known for the secondary and/or tertiary type crushing of inert material, that is, able to obtain the desired granulometry of the material to be crushed.
Known crushing mills normally comprise a distribution unit, consisting of a rotor on the periphery of which a plurality of blades are fixed.
This distribution unit has the function of receiving the material entering from a suitable feed unit and to suitably direct it to a crushing unit, which is normally disposed below the distribution unit.
The distribution unit is housed inside a distribution chamber, which has an upper aperture in order to receive the material to be crushed and a lower aperture in order to unload it toward the bottom, where the crushing unit is.
In its turn the crushing unit comprises a crushing rotor, on the periphery of which a plurality of hammers are fixed, or functionally similar elements, to crush the material.
The crushing rotor is positioned inside a crushing chamber, which is peripherally delimited by wall elements suitably shaped and having a protruding profile with ridges facing toward the inside of the crushing chamber or toward the rotor.
The shaped elements are normally disposed adjacent to each other, forming a wall or shield around the crushing rotor and shaped toward the inside of the crushing chamber. The elements are supported and maintained in position by one or more shield-carrying elements disposed outside the crushing chamber and on which they are mounted.
The hammers of the crushing rotor, as they turn, throw the material coming from the distribution unit toward the shield.
The ridged profiles of the shield cause the material to be crushed following the impact with the material thrown toward it.
The distribution chamber and the crushing chamber are normally housed inside a box-like structure, which can be at least partly opened in order to define a first completely closed position, in which all the elements that make up the box-like structure are close to each other and define a closed internal volume, and a second partly open position, in which at least some of the elements are in a position distanced from each other, defining at least an access aperture toward the inside of the box-like structure.
When the crushing mill is working, the box-like structure is in the completely closed position, so that the crushing of the material can occur in safe conditions inside the crushing chamber.
In order to carry out any necessary maintenance operations, the box-like structure is brought into the at least partly open position in order to allow the entrance of at least one operator inside the mill in order to carry out the repairs, substitution of worn parts etc.
In the state of the art a solution is known in which the box-like structure comprises a lower box-like element and two lateral movable casings, identical and opposite each other, mounted above the structure.
Between the two lateral casings two fixed walls are interposed, assembled on the lower box-like element and parallel to each other.
Each of the lateral casings is hinged along one of its sides to the lower box-like element by means of a hinging element, so as to enable it to partly rotate with respect to the hinging element.
The shield-carrying elements are located inside the lateral casings.
The rotation of each lateral casing selectively occurs by means of a linear actuator, suitably positioned and attached by one of its ends to the lower box-like structure and by the other end to the lateral casing to be moved.
Each lateral casing is selectively rotated toward the outside of the box-like structure, one in a clockwise direction and the other in an anti-clockwise direction, so as to obtain a semi-opening of the box-like structure, or toward the inside of the box-like structure in order to obtain the closing of said box-like structure.
The semi-opening allows access to the inside of the crushing chamber so as to carry out maintenance on the distribution unit, such as for example to replace the worn out blades, the maintenance of the shield or other.
One disadvantage of known crushing mills is that the box-like structure, in a semi-open position with both the lateral casings open, does not allow a complete view of the distribution unit, in that the casings partly obscure the view of internal parts of it, and does not allow easy access to it.
Because of this it is often necessary for at least one operator to enter the machine, when maintenance operations have to be carried out to the distribution unit, such as for example to replace worn blades.
This complicates the maintenance operations of the mill. As a consequence the maintenance times are long and the down-times of the machine connected to such maintenance operations are considerable.
Moreover, the need for an operator to enter the crushing mill in order to carry out maintenance operations, for example to the distribution unit or the crushing unit, constitutes a safety problem for the operators themselves, who check, supervise and do maintenance to the plant.
Purpose of the present invention is to improve safety conditions connected to the maintenance operations of the crushing mill, making access to the inside sections of the mill easily accessible for the operators.
In this way maintenance operations themselves are made easier, reducing the maintenance time needed.
The Applicant has devised, tested and embodied the present invention to overcome the shortcomings of the state of the art and to obtain these and other purposes and advantages.